Why

With the re-institution of Rails engines in Rails 2.3, we decided to convert
Clearance to engine. The process was relatively painless, the code is far
cleaner, and we think we were able to scratch all our itches.

Philosophy

We highly recommend that you use the Cucumber features
that come with Clearance to test the integration of the engine with your app:

script/generate clearance_features

You no longer run Clearance’s generated Shoulda & Factory Girl tests within
your test suite. That code is unit tested internally. Use the Cucumber features
to test integration. If and when you override functionality, write your own unit
tests.

Overriding

We haven’t and probably won’t ever move Clearance beyond email and password
authentication, despite frequent requests. We’re focused on clean code that
works for the baseline authentication we’ve written over and over again for
clients.

A huge part of clean code that works means that overriding
Clearance needs to be painless. The change to an engine helps achieve that
goal.